450 Proceedings of Societies . [June, 
the latter. To sound the call it is only necessary to send a sharp 
puff of wind up the speaking-tube, and the reed gives out a note 
which is heard throughout a room at the distant end. Speaking 
and cornet music was transmitted to the instrument exhibited, 
between the third storey over the hall and the meeting. It was 
very distinct and audible several feet from the receiver. Speaking 
done some 30 feet from the transmitter was also sent. Con- 
versation was likewise carried on while considerable noise was 
being made in the room. 
Prof. W. F. Barrett then gave an account of some attempts 
which he had made to overcome the induction clamour on tele- 
phones caused by the ordinary telegraph currents on neighbouring 
wires. He had tried recently the Bell telephone on a line from 
Dublin to Armagh, 95 miles long, but the induction noises com- 
pletely stifled the speaking, whereas the Edison transmitter gave 
good results. The clamour could be got rid of either by neutral- 
ising the induction currents or by eliminating the noises from 
the speech. 
Mr. Wollaston pointed out that a perfect cure for induction on 
underground wires consisted in twisting the going and returning 
wire of the telephone circuit round each other. 
Mr. Wilson then read a paper “ On the Divisibility of the 
Electric Light by Incandescence.” The question of divisibility 
resolves itself into our being able to divide a single incandescent 
source into a number of smaller ones giving the same total 
illumination. The author concludes that this can be done by 
arranging the subdivided sources in “ multiple arc,” or parallel 
circuits, provided the total mass, length, and sectional area of 
the united sources be the same as in the original single source. 
The objection that increased radiation from the various sources 
would diminish the first total of light and heat can be met by 
making the smaller wires still smaller than is theoretically 
required so as to generate more heat. The author regards the 
“ voltaic arc ” as probably falling under the same law, the mass, 
however, being smaller in this case. 
Dr. Coffin then exhibited a Trouve Polyscope, which consists 
of a small hand incandescent platinum wire electric light, de- 
signed for illuminating the more inaccessible cavities of the 
body in surgical examinations. The current is supplied by a 
Plante secondary battery, and the light is half enclosed in a 
small silver reflector, fitted with a convenient handle. The ap- 
paratus is portable. Dr. Coffin found that it was open to several 
objections, which he has remedied. Dr. Coffin has superseded 
the secondary battery by a Leclanche battery of eight elements, 
made by Messrs. Coxeter and Sons, in which the carbon pole is 
replaced by a copper plate faced with platinum, and no porous 
diaphragm is employed. This gives a constant light for hours. 
